Switch, Network System and Traffic Movement Method

1. A switch comprising: a transfer control section comprising: a memory, the memory comprising a plurality of entries, each entry comprising: MAC address information, line identification information comprising: stored sending destination line information, stored receiving discrimination line information, and an incompatibility permission flag having a permissible state and an impossible state; wherein the transfer control section is configured to: receive a frame from a source line and send the frame to another switch or terminal through a destination line; the frame comprising a source MAC address and a destination MAC address, the source line comprising source sending destination line information and source receiving discrimination line information; the destination line comprising destination line information; search the memory for a single entry comprising the source MAC address and the source receiving discrimination line information, wherein the transfer control section is configured to use the source MAC address and source receiving discrimination line information as search keys to search the memory; if an entry comprising the source MAC address and the source receiving discrimination line information is identified, then the transfer control section is configured to determine that the source MAC address and the source receiving discrimination line information are already stored in the memory; else if the source MAC address is not found in the memory, then the transfer control section is configured to add an entry to the memory comprising the source MAC address, source sending destination line information and source receiving discrimination line information; else if the source MAC address is found in the memory, but the entry comprising the source MAC address has a different stored receiving discrimination line information than the source receiving discrimination line information of the source line, then the transfer control section is configured to: update the stored receiving discrimination line information with the receiving discrimination line information of the source line that received the frame, if the state of the compatibility flag is permissible; update the stored discrimination receiving line information and the sending destination line information with the receiving discrimination line information and the sending destination line information of the source line that received the frame, if the state of the compatibility flag is impossible; and search the memory for a single entry comprising the destination MAC address, wherein the transfer control section is configured to use the destination MAC address as a search key to: select the stored destination line information in the entry comprising the destination MAC address information to function as a destination line, if the destination MAC address is found, instruct the switching mechanism to transfer the frame via the destination line, if the destination MAC address is found, and instruct the instruct the switching mechanism to transfer the first frame by flooding, if the destination MAC address is not found.

2. The switch of claim 1 , wherein the switch is connected to a management device configured to issue control information to the switch; wherein the control information comprises: incompatibility permission flag object line information, movement source line information, movement destination line information, and incompatibility permission flag information; and the switch further comprises a switch control section configured to: receive the control information; instruct the transfer control section to search the memory for an entry comprising the stored sending destination line information with the incompatibility permission flag object line information, the incompatibility permission flag object line information functioning as a search key, instruct the memory to overwrite the incompatibility permission flag of the entry comprising the stored sending destination line information with the incompatibility permission flag information, instruct the transfer control section to search the memory for an entry comprising the stored sending destination line information with the movement source line information as the key, and instruct the memory to overwrite the sending destination line of the entry comprising the stored sending matched entry in accordance with the movement destination line information.

3. The switch of claim 1 , wherein the switch comprises: a first line control section for controlling a first line; a second line control section for controlling a second line, and an nth line control section for controlling an nth line.

4. The switch of claim 2 , wherein the switch is configured to change an incompatibility permission flag of the memory from permissible to impossible after traffic has been transferred from the source line to the destination line.

5. The switch of claim 2 , wherein the memory is a filtering database, and the switch is a layer 2 switch.

6. A network system comprising: a first switch comprising: a transfer control section comprising: a memory, the memory comprising a plurality of entries, each entry comprising: MAC address information, line identification information comprising: stored sending destination line information, stored receiving discrimination line information, and an incompatibility permission flag having a permissible state and an impossible state; wherein the transfer control section is configured to: receive a frame from a source line and send the frame to another switch or terminal through a destination line; the frame comprising a source MAC address and a destination MAC address, the source line comprising source sending destination line information and source receiving discrimination line information; the destination line comprising destination line information; search the memory for a single entry comprising the source MAC address and the source receiving discrimination line information, wherein the transfer control section is configured to use the source MAC address and source receiving discrimination line information as search keys to search the memory; if an entry comprising the source MAC address and the source receiving discrimination line information is identified, then the transfer control section is configured to determine that the source MAC address and the source receiving discrimination line information are already stored in the memory; else if the source MAC address is not found in the memory, then the transfer control section is configured to add an entry to the memory comprising the source MAC address, source sending destination line information and source receiving discrimination line information; else if the source MAC address is found in the memory, but the entry comprising the source MAC address has a different stored receiving discrimination line information than the source receiving discrimination line information of the source line, then the transfer control section is configured to: update the stored receiving discrimination line information with the receiving discrimination line information of the source line that received the frame, if the state of the compatibility flag is permissible; update the stored discrimination receiving line information and the sending destination line information with the receiving discrimination line information and the sending destination line information of the source line that received the frame, if the state of the compatibility flag is impossible; search the memory for a single entry comprising the destination MAC address, wherein the transfer control section is configured to use the destination MAC address as a search key to: select the stored destination line information in the entry comprising the destination MAC address information to function as a destination line, if the destination MAC address is found, instruct the switching mechanism to transfer the frame via the destination line, if the destination MAC address is found, and instruct the instruct the switching mechanism to transfer the first frame by flooding, if the destination MAC address is not found; a second switch connected to the first switch via the destination line; and a management device that outputs control information to the first switch, the second switch, or both.

7. The switch of claim 6 , wherein the control information comprises: incompatibility permission flag object line information, movement source line information, movement destination line information, and incompatibility permission flag information; and the first switch further comprising a switch control section configured to: receive the control information; instruct the transfer control section to search the memory for an entry comprising the stored sending destination line information with the incompatibility permission flag object line information, using the incompatibility permission flag object line information functioning as a search key, instruct the memory to overwrite the incompatibility permission flag of the entry comprising the stored sending destination line information with the incompatibility permission flag information, instruct the transfer control section to search the memory for an entry comprising the stored sending destination line information with the movement source line information as the key, and instruct the memory to overwrite the sending destination line of the entry comprising the stored sending matched entry in accordance with the movement destination line information.

8. A method of routing traffic with a switch, the method comprising: receiving a frame from a source line; sending the frame to another switch or terminal through a destination line; wherein the frame comprises a source MAC address and a destination MAC address, the source line comprises source sending destination line information and source receiving discrimination line information; the destination line comprises destination line information; providing a transfer control section comprising: a memory, the memory comprising a plurality of entries, each entry comprising: MAC address information, line identification information comprising: stored sending destination line information, stored receiving discrimination line information, and an incompatibility permission flag having a permissible state and an impossible state; searching the memory for a single entry comprising the source MAC address and the source receiving discrimination line information, wherein searching comprises using the source MAC address and source receiving discrimination line information as search keys to search the memory; determining the source MAC address and the source receiving discrimination line information are already stored in the memory, if an entry comprising the source MAC address and the source receiving discrimination line information is identified; adding an entry to the memory comprising the source MAC address, source sending destination line information and source receiving discrimination line information, if the source MAC address is not found in the memory; updating the stored receiving discrimination line information with the receiving discrimination line information of the source line that received the frame, if the state of the compatibility flag is permissible, and if the source MAC address is found in the memory, but the entry comprising the source MAC address has a different stored receiving discrimination line information than the source receiving discrimination line information of the source line; updating the stored discrimination receiving line information and the sending destination line information with the receiving discrimination line information and the sending destination line information of the source line that received the frame, if the state of the compatibility flag is impossible, and if the source MAC address is found in the memory, but the entry comprising the source MAC address has a different stored receiving discrimination line information than the source receiving discrimination line information of the source line; searching the memory for a single entry comprising the destination MAC address, wherein searching comprises using the destination MAC address as a search key; selecting the stored destination line information in the entry comprising the destination MAC address information to function as a destination line, if the destination MAC address is found; transferring the frame via the destination line, if the destination MAC address is found; and transferring the first frame by flooding, if the destination MAC address is not found.

9. The method of claim 8 , comprising connecting the switch to a management device configured to issue control information to the switch, wherein the control information comprises: incompatibility permission flag object line information, movement source line information, movement destination line information, and incompatibility permission flag information; and receiving the control information with the switch; searching the memory for an entry comprising the stored sending destination line information with the incompatibility permission flag object line information, the incompatibility permission flag object line information functioning as a search key; overwriting the incompatibility permission flag of the entry comprising the stored sending destination line information with the incompatibility permission flag information; searching the memory for an entry comprising the stored sending destination line information with the movement source line information as the key; and overwriting the sending destination line of the entry comprising the stored sending matched entry in accordance with the movement destination line information.